Global regulatory movements as part of the Montreal protocol and beyond have paved the way for the development and implementation of low GWP refrigerants in air conditioning and heat pump as well as refrigeration applications. The refrigerant choices for different applications are determined by their thermodynamic and physical properties to ensure a balance can be achieved between system performance and necessary use of resources for both raw materials of construction and the energy required for operation. This paper will provide an updated view and general assessment of low GWP refrigerants and their properties and viability for air conditioning and heat pump applications. An evaluation of direct emission impact based on global warming potential and indirect emission considerations that are based on the operating emissions determined by the efficiency of the application is performed. This concept is then expanded to include the resource use due to the design requirements of the equipment based on the thermodynamic properties of the refrigerant in consideration. This cost effectiveness threshold (CET) aims to support the decision-making process in comparing different refrigerant options.